The invention relates to an apparatus for storing spent fuel elements and in particular to a fuel storage apparatus which is resistant to seismic disturbances.
Nuclear fuel assemblies are still active after being removed from a nuclear reactor and, accordingly, are stored in pools of water until their reactivity decays to an acceptable level. The fuel assemblies are spaced either with or without poison material to form a noncritical array and to permit the water of the pool to flow over the elements to cool them.
Various gridwork assemblies both with and without fuel assembly encircling boxes have been supported from the floor of the pool and braced against the walls. The structure must be designed to allow for some expansion since the fuel storage rack will expand differently than the concrete in which it is located. The rack must also be attached to resist seismic forces either by bracing on the walls or by firm attachment to the floor. In either case, provisions for expansion must also be made at these locations.
Since the earthquake forces are transmitted through the storage rack and/or the fuel assemblies and the components of the rack, the individual members must be designed to withstand the resultant forces. This results in expensive construction for a required safe storage rack.